Background: Functional disorders of the anus and rectum affect 10-20% of the population.Tests of anorectal function can provide useful information regarding the pathophysiology of the disorders that affect continence and defecationAim: anorectal physiological assessment of patients with functional obstructive defecation using anorectal manometry, balloon expulsion test and surface EMG and compare their results with normal controls.Subjects and methods: 20 patients that fulfilling Rome III criteria of functional constipation underwent anorectal physiological testing using anorectal manometry, balloon expulsion test and surface EMG in addition to 10 healthy individuals as a normal controls.Results: Mean resting pressure in patients and normal controls was 81 and 60 mmHg respectively. The anal canal pressure during straining in patients showed paradoxical increase in relation to the resting pressure in 17 patients (85%) and 3patients (15%) showed decrease by less than 20% of the resting pressure, however in normal controls decreased by more than 20%. Recto anal inhibitory reflex was present in both groups. There was marked hyposensation in 12 patients(60%),4 patients (20%) showed mild anorectal hyposensation, and 4 patients (20%) showed normal rectal sensory thresholds, However in control group there was mild rectal hyposensation in 5 volunteers (50%). All constipated patients failed to expel a 50 cc water inflated balloon within 2 minute and 100% of normal controls succeeded to expel the balloon in less than one minute. Surface EMG showed paradoxical increase in average MUAP base line in 17 patients (85%) and remaining 3 patients (15%) showed mild decrease in average MUAP base line, however in normal controls it showed decrease in average MUAP base line.Conclusion: Anorectal physiological testing using anorectal manometry is very helpful in diagnosis of functional obstructive defecation among constipated patients. Balloon expulsion test is a good screening test for identification of functional constipation.